As well as the prestige that comes with winning the prize, Mitchell picked up a cheque for USD 75,000.

Chair of the Grantham prize jury Philip Meyer said: 'You cannot put this book down without understanding that, for life on earth to continue as it is, the ocean from which we evolved must remain healthy.'

Three journalists were also nominated for Awards of Special Merit for their outstanding environmental reporting. They were Dan Egan of the Milwaukee Journal Sentinel, Cleo Paskal, author of Global Warring, and Hedrick Smith Productions for their Poisoned Waters documentary.

Global Warring highlights the environmental catastrophes that are most likely to cause international conflict.